blocks|key|1691085|text|setattr(x,+attr,+'magic')|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1691086|有关它的帮助，请访问：|unstyled|1691087|>>>+help(setattr)
Help+on+built-in+function+setattr+in+module+__builtin__:

setattr(...)
++++setattr(object,+name,+value)
++++
++++Set+a+named+attribute+on+an+object;+setattr(x,+'y',+v)+is+equivalent+to
++++``x.y+=+v''.|1691088|但是，您应该注意到，您不能对object的“纯”实例执行此操作。但很可能你有一个简单的object子类，在那里它会工作得很好。我强烈建议共和党人永远不要让object成为那样的实例。|offset|length|style|CODE|1691089|entityMap^0|0|0|0|E|6|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|R|8|@]|9|@]|A|$]]|$1|G|3|H|5|6|7|S|8|@]|9|@]|A|$B|C]]|$1|I|3|J|5|F|7|T|8|@$K|U|L|V|M|N]]|9|@]|A|$]]|$1|O|3|-4|5|F|7|W|8|@]|9|@]|A|$]]]|P|$]]

<pre><code>setattr(x, attr, 'magic')
</code></pre>
For help on it:
<pre class="lang-none prettyprint-override"><code>&gt;&gt;&gt; help(setattr)
Help on built-in function setattr in module __builtin__:

setattr(...)
 setattr(object, name, value)
 
 Set a named attribute on an object; setattr(x, 'y', v) is equivalent to
 ``x.y = v''.
</code></pre>
However, you should note that you can't do that to a &quot;pure&quot; instance of <code>object</code>. But it is likely you have a simple subclass of object where it will work fine. I would strongly urge the O.P. to never make instances of object like that.

blocks|key|1691141|text|通常，我们为此定义类。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1691142|class+XClass(+object+):
+++def+__init__(+self+):
+++++++self.myAttr=+None

x=+XClass()
x.myAttr=+'magic'
x.myAttr|code-block|syntax|javascript|1691143|但是，在某种程度上，您可以使用setattr和getattr内置函数来实现这一点。但是，它们不能直接在object实例上工作。|offset|length|style|CODE|1691144|>>>+a=+object()
>>>+setattr(+a,+'hi',+'mom'+)
Traceback+(most+recent+call+last):
++File+"<stdin>",+line+1,+in+<module>
AttributeError:+'object'+object+has+no+attribute+'hi'|1691145|然而，它们确实在各种简单的类上工作。|1691146|class+YClass(+object+):
++++pass

y=+YClass()
setattr(+y,+'myAttr',+'magic'+)
y.myAttr|1691147|entityMap^0|0|0|F|7|N|7|1F|6|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|W|8|@$I|X|J|Y|K|L]|$I|Z|J|10|K|L]|$I|11|J|12|K|L]]|9|@]|A|$]]|$1|M|3|N|5|D|7|13|8|@]|9|@]|A|$E|F]]|$1|O|3|P|5|6|7|14|8|@]|9|@]|A|$]]|$1|Q|3|R|5|D|7|15|8|@]|9|@]|A|$E|F]]|$1|S|3|-4|5|6|7|16|8|@]|9|@]|A|$]]]|T|$]]

Usually, we define classes for this.

<pre><code>class XClass( object ):
 def __init__( self ):
 self.myAttr= None

x= XClass()
x.myAttr= 'magic'
x.myAttr
</code></pre>

However, you can, to an extent, do this with the <code>setattr</code> and <code>getattr</code> built-in functions. However, they don't work on instances of <code>object</code> directly. 

<pre><code>&gt;&gt;&gt; a= object()
&gt;&gt;&gt; setattr( a, 'hi', 'mom' )
Traceback (most recent call last):
 File "&lt;stdin&gt;", line 1, in &lt;module&gt;
AttributeError: 'object' object has no attribute 'hi'
</code></pre>

They do, however, work on all kinds of simple classes.

<pre><code>class YClass( object ):
 pass

y= YClass()
setattr( y, 'myAttr', 'magic' )
y.myAttr
</code></pre>

blocks|key|1691192|text|假设x是一个对象，那么你可以用两种方法来做。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1691193|x.attr_name+=+s+
setattr(x,+'attr_name',+s)|code-block|syntax|javascript|1691194|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

let x be an object then you can do it two ways

<pre><code>x.attr_name = s 
setattr(x, 'attr_name', s)
</code></pre>

blocks|key|1476153|text|在类中也可以很好地工作：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1476154|def+update_property(self,+property,+value):
+++setattr(self,+property,+value)|code-block|syntax|javascript|1476155|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Also works fine within a class:
<pre><code>def update_property(self, property, value):
 setattr(self, property, value)
</code></pre>

Suppose I have a python object <code>x</code> and a string <code>s</code>, how do I set the attribute <code>s</code> on <code>x</code>? So:

<pre><code>&gt;&gt;&gt; x = SomeObject()
&gt;&gt;&gt; attr = 'myAttr'
&gt;&gt;&gt; # magic goes here
&gt;&gt;&gt; x.myAttr
'magic'
</code></pre>

What's the magic? The goal of this, incidentally, is to cache calls to <code>x.__getattr__()</code>.

How do you programmatically set an attribute?

假设我有一个python对象x和一个字符串s，如何在x上设置属性s？所以：>>> x = SomeObject()>>> attr = 'myAttr'>>> # magic goes here>>> x.myAttr'magic'有什么神奇之处？顺便说一句，这样做的目的是缓存对x.__getattr__()的调用。

问如何以编程方式设置属性？
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